The invention relates to a suction-appliance attachment having a suction channel, there being disposed in the suction channel a component which is to be monitored in terms of insertion and downstream of the component, as seen in the flow direction, a valve which has a movable closure body in the form of a valve ball secured freely in a valve chamber.
Mechanical solutions are known as means for ensuring reliable insertion. For this purpose, use is made, for example, of levers or similarly actuated elements which, when the necessary components are not inserted, block the functioning of the appliance to a greater or lesser extent. On account of the mechanics, such systems are susceptible to being jammed, destroyed or manipulated. Furthermore, in the case of suction-appliance attachments for the wet-cleaning of surfaces, it is known to provide a movable closure body, for example in the form of a ball, which can be triggered when exposed to moisture. Such an arrangement is known, for example, from DE-A1 196 54 335. The contents of this laid-open application are hereby included in full in the disclosure of the present invention, also for the purpose of incorporating features of this patent application in claims of the present invention.
In respect of the above-described prior art, it is an object of the invention to provide a means for ensuring reliable insertion for a suction-appliance attachment of the type in question which is disposed such that it is protected against being jammed, destroyed and manipulated and which, when a component is not inserted or an incorrect component is inserted, suppresses the suction-volume stream.
This problem is solved first and foremost by the subject matter of claim 1, this being based on the fact that an inlet cross-section of the valve chamber, which is reduced in size by insertion of the component which is to be monitored, effects a flow deflection which is sufficient for the opening position of the valve, it being the case that, when the component is not inserted, the opening cross-section is large enough for the valve ball to be pressed into its closure position by the flow pressure. By virtue of a particular cross-sectional profiling of the suction channel and/or of the valve ball in the region of the valve formed, the flow around the closure body, when the correct component is inserted, is configured such that the axial forces acting keep the closure body in a state of equilibrium. These forces are, for example, the weight forces resulting from the dynamic and static pressure and also the frictional forces as well as, in the case of means according to the invention for ensuring reliable installation being disposed in a suction-appliance attachment for the wet-cleaning of surfaces, the momentum and/or the impact forces. As is known from the patent application mentioned in the introduction, the closure body, in the case of the normal oncoming flow being superimposed by a mass flow of increased density, is displaced, by this additional momentum, into a closure position from its position of equilibrium, which forms the valve-opening position. This effect is utilized according to the invention in order to form the means for ensuring reliable insertion. When a component is not inserted or when an incorrect component is inserted, the flow deflection which is required for the state of equilibrium in the valve in the open position is thus not provided, so that the flow pressure to which the closure body is then subjected presses this closure body more or less abruptly into the closure position. The flow deflection which is required for the opening position of the valve can thus only be set by the correct component being inserted. As a result of this configuration, with the exception of the closure body formed as a valve ball, there is no need for any further movable parts in order to form the means for ensuring reliable insertion. Furthermore, the configuration according to the invention also gives a high level of protection against manipulation, since the closure body, formed as a ball, is in a concealed position, inaccessible from the outside. Providing a valve ball further counteracts jamming of the closure body. As a further advantage of the means according to the invention for ensuring reliable insertion, it should be pointed out that this means operates without using electrical energy, as a result of which there is no need for any energy converters, such as for example motors or electromagnets. It is further found to be advantageous that the means according to the invention for ensuring reliable insertion can be used as often as desired. The configuration according to the invention ensures interruption of the suction-volume stream when the component is not inserted or an incorrect component is inserted. As a result, the user of the suction-appliance attachment provided with this means for ensuring reliable insertion is obliged to insert the correct component in order to operate the appliance. In the case of being used in a suction-appliance attachment for the wet-cleaning of surfaces, a component which is to be monitored in terms of insertion may be a sponge body for taking up the absorbed cleaning liquid, the insertion of which sponge body is imperative for maintaining reliability. In a test to operate the appliance without a system-compatible storage/sponge body, the closure body, formed as a valve ball, is pressed abruptly into the closure position, in order to interrupt the volume stream, by the increased flow pressure. It is thus not possible, in this example, for any liquid to be taken in without control. If, in contrast, the correct sponge body is properly inserted, then, by virtue of the flow deflection provided here in the region of the inlet cross-section, the closure body remains in its position of equilibrium, which defines the opening position of the valve and which the closure body only leaves when a mass-flow threshold value is exceeded, for example once the maximum liquid absorption of the sponge body has been exceeded. This configuration according to the invention provides positionally independent detection of necessary components in minimal installation space, while simultaneously providing a fluidic switching signal with a large switching-force range. An advantageous further development of the subject matter of the invention provides that the inlet cross-section is formed as a perforated base. The openings provided in the perforated base are dimensioned and positioned such that, when a correct component is inserted, a flow deflection which causes the valve to open is provided in the region of the inlet cross-section. If, in contrast, no component or an incorrect component is inserted, then the air flowing through the further openings in the perforated base effects disruption of the equilibrium-providing flow deflection. Furthermore, it is provided that the perforated base has a central clearance through which the valve ball does not pass. This clearance preferably forms the inlet cross-section of the valve chamber, it being further preferred for the channel cross-section of the valve chamber to be greater than the clearance cross-section. As a result of the fact that, in a further preferred manner, the valve ball has a diameter which is larger than the clearance, an in particular sharp-edged deflection of the volume stream which enters into the valve chamber from the clearance, and flows around the valve ball, effects a supporting vortex in the region of the closure body, so that the latter remains in the position of equilibrium, which defines the opening position of the valve. If, in contrast, when the component is not inserted or an incorrect component is inserted, further openings of the perforated base are released, then the air flowing in through the further openings disrupts the supporting vortex, so that the valve ball, entrained by the flow, is pressed into the closure position. Furthermore, it is proposed that the component which is to be monitored has a flow clearance adapted to the central clearance. As a result of this configuration, there is no disruption to the flow behaviour in the proper state, i.e. when the correct component is inserted, in the region of the central clearance. It may further be provided that the perforated base has symmetrically distributed openings which are disposed, for example, in a uniformly distributed manner around the central clearance of the perforated base. When the correct component is inserted, these openings are closed by this component, so that the element for ensuring reliable insertion operates satisfactorily. If, in contrast, no component is inserted or an incorrect component is inserted, then the monitoring cross-sections, which are kept open at least partially as a result, cause the closure body to be displaced into the valve-closure position. The openings here may be of any desired shape, the overall size of the opening cross-sections being in the range from 10-50% of the inflow cross-section, i.e. of the cross-section of the clearance. As an alternative to the previously described alignment of the openings, it may also be provided that the perforated base has non-symmetrically distributed openings. Finally, the configuration here may be selected such that an opening is formed as a circle-segment-like slot which extends in a region of the perforated base between the central clearance and the valve-chamber wall. Adaptation of the closure-body weight makes it possible to set the reaction threshold and the reaction time. It is thus possible to use, for example, an HDPE plastics ball having a weight from 1 to 10 grams.